An electric circuit is known from European Patent Publication No. EP 1 139 422, where a plurality of series circuits having a piezoelectric element and a transistor are connected in parallel. A first measuring shunt is grounded in series with the parallel circuit. The parallel circuit is also connected, via an inductor coil, to the shared connection point of two transistors grounded in series. A series circuit of a capacitor and a second measuring shunt is grounded in parallel to the two transistors.
In European Patent Publication No. EP 1 139 442, a check is performed prior to a charging operation or a discharging operation, i.e., prior to a current flowing through one of the piezoelectric elements, to determine whether the piezoelectric element has a short circuit. For this purpose, a check is performed during a predefined time period prior to the charging or discharging operation to determine whether a current is flowing through one of the measuring shunts. If this is the case, there is a fault.
This check requires a certain amount of time which therefore cannot be used for the charging or discharging operation. As a result, for example, small injected amounts in the case of a fuel injection system of a motor vehicle can be metered by the piezoelectric elements only with reduced accuracy.